add test case for pos=None

sujanasowrirajan · sujanasowrirajan · commit 9f1cae6f9f8f · 2019-12-24T22:30:42.000+05:30
diff --git a/lib/matplotlib/tests/test_category.py b/lib/matplotlib/tests/test_category.py
@@ -154,6 +154,7 @@ def test_StrCategoryFormatter(self, ax, ydata):
         labels = cat.StrCategoryFormatter(unit._mapping)
         for i, d in enumerate(ydata):
             assert labels(i, i) == d
+            assert labels(i, None) == d
 
     @pytest.mark.parametrize("ydata", cases, ids=ids)
     @pytest.mark.parametrize("plotter", PLOT_LIST, ids=PLOT_IDS)
